Ioversol is disclosed as a useful nonionic x-ray contrast agent in U.S. Pat. No. 4,396,598. 5-[N-(2-acetoxyethyl)-acetoxyacetamido]-N,N'-bis(2,3-diacetoxypropyl)-2,4, 6-triiodoisophthalamide, hereinafter referred to as "Compound A", having the following structure: ##STR1## is an intermediate compound in the production of ioversol. The compound of Formula I and its use in the production of ioversol is likewise disclosed in U.S. Pat. No. 4,396,598 incorporated herein by reference. Compound A as disclosed in U.S. Pat. No. 4,396,598, may be produced by adding 2-bromoethylacetate and potassium carbonate to a solution of 5-acetoxyacetamido-N,N'-bis(2,3-diacetoxypropyl)-2,4,6-triiodoisophthalami de, illustrated in Formula II below and hereinafter referred to as "Compound B", ##STR2## in dimethylsulfoxide and stirring until the reaction is complete. The resulting Compound A is then hydrolyzed with water containing sulfuric acid, preferably in small amounts within the range of approximately zero to 25 percent, to produce ioversol.
The procedure for producing ioversol is well documented and heretofore required an extensive purification process to remove impurities formed therein during the above-described synthesis.
An improved process that eliminates the need for such an extensive purification process for the purification of crude ioversol by significantly decreasing the impurities formed therein during synthesis, is desired as an enhanced and/or more cost efficient production method. It is an object of the present invention to meet these needs.